1. Technical Field
The invention relates to the field of night vision devices that enable a viewer to observe objects at night or during other low-light conditions. More particularly, this present invention relates to a system to prevent the undesired viewing into an interior space or compartment by an external or outside observer.
2. Background Art
Night vision devices are well known. A common type of a night vision device is based on an image intensification technology and is used to provide soldiers, aviators, and sailors with the ability to view objects at night or during other low light conditions.
A common scenario associated with the use of a night vision device is a soldier using a night viewer, such as a night vision goggle ("NVG") AN/PVS-7 or others, to observe a battlefield scene at night. If the night-time battlefield scene includes people sitting in a vehicle, it is likely that at some point the vehicle occupants will need light to illuminate their compartment to complete operations. Unless otherwise protected, the light source will cast a glow that is visible to the observer outside the vehicle. To prevent or minimize observation by an "unfriendly" soldier using a NVG, a "blackout mode of operation" has been adopted to counteract the observation advantages that the "unfriendly" NVG equipped soldier may have on the battlefield. Consequently, this scenario has prompted a concern with the tactical risk associated with any lighting used in the night vision goggle ("NVG") blackout mode of operation.
Internal lighting for vehicles, aircraft, and naval warships is clearly required to permit continued use of the vehicles in battle while in the blackout mode of operation. In response night viewer compatible flashlights have been provided as one source of lighting. Alternatively, IR illuminators have been provided and incorporated into night vision systems equipment. The IR illuminators provide lighting at a frequency that is not normally observable without NVG. In both cases the lighting poses a genuine and significant tactical threat from enemy night vision devices.
A technology solution is needed to provide illumination within a vehicle also eyeing the issue of tactical risk from the enemy use of night vision devices.
While the above cited known solutions introduce a number of noteworthy advances and technological improvements within the art, none completely fulfills the specific objectives achieved by this invention.